1. Field of the Invention
The present invention relates to an information processing apparatus and a method which enable editing data tracks recorded in a predetermined data area by manipulating data stored in a predetermined table. In particular, the present invention relates to a disc apparatus handling a well-known MD (Mini Disc) which is a disc information recording medium, which has recently come into wide use. Through the disc apparatus, by manipulating data stored in a rewriteable UTOC region, music recorded in a rewriteable user data region may be edited. Here, the term `track` is used for meaning a succession of data such as music.
2. Description of Related Art
There are three kinds of MD, a pre-master disc which is used only for reproducing recorded data, a recordable disc which is used for both recording data therein and reproducing data therefrom, and a hybrid disc which has characteristics of both the pre-master disc and recordable disc. Each of the recordable disc and hybrid disc has a non-rewriteable TOC region, and a the rewriteable UTOC region, rewriteable user data region. The user data region is a collection of recording medium sections which may be used for recording data tracks (music in this case). The recording medium sections (simply referred to as `parts`, hereinafter) have digital audio data successively recoded therein.
The UTOC region has a header portion, a portion for storing the number of a first tune, a portion for storing the number of a last tune, a P-EMPTY (Pointer for the first EMPTY slot on the parts table), a P-FRA (Pointer for the start address of the FReely recordable Area), track-data portions (P-TNO(1), P-TNO(2), P-TNO(3), . . . P-TNO(n), Pointers for the start addresses of Track 1, Track 2, Track 3, . . . Track n (n is a natural number) ), and part-data portions (part descriptors). Each part-data portion is a portion for storing data which points to a respective part in the user data region. The part data stores addresses of particular tunes recorded on the disc and Link-P's (Link Pointers). For a part, a start address and an end address in the user region of the disc are stored, and further Link-P is stored if necessary. The Link-P is a pointer pointing to a possible subsequent part. If a tune consists of a plurality of successive parts, the Link-P is used for pointing to a part subsequent to a relevant part. If a relevant part has no subsequent part, that is, the relevant part is a last part in a tune, `0` is stored as the Link-P.
The P-FRA portion is used for managing part-data portions pointing to data-free parts (having no substantial data) and/or data-deleted parts (a deletion operation has been performed on data stored therein). The P-FRA portion stores pointer information pointing to a top of part-data portions pointing to such a freely-usable storage area as the data-free parts and/or data-deleted parts. Each of the track-data portions is a portion for storing pointer information pointing to a respective track stored in the user data region of the disc. Specifically, the track-data portions are used for managing parts having effective data stored therein. In each track-data portion, a number of a part-data portion indicating a top part of a respective tune is stored.
The disc apparatus for recording data in and reproducing data from the MD uses the UTOC information and thus may store in the MD a maximum of 255 tunes. By manipulating the UTOC information, any tunes recorded may be coupled to one another and any tune may be deleted. In such editing operations as tune deletion and tune coupling, it is not necessary to directly modify information (music data) stored in the user data region. The editing operations may be performed, through the manipulation of the UTOC information, by changing part allocation, changing part allocation after dividing a part, or the like. Thus, each time another tune is recorded, and each time recorded tunes are edited, part-data portions are consumed.
In a disc apparatus such as that described above in the related art, once a data deletion operation has been once performed in an editing operation and thus the UTOC region has been modified accordingly, although the relevant track or music data has not been actually removed from relevant parts of the user data area, relevant part-data portions automatically belong to the P-FRA. That is, in order to effectively use the user data region, in particular, parts in which data has a deletion operation performed thereon, the relevant parts in the user data region are labeled as being a `freely-usable area`. Once the relevant part-data portions have belonged to the P-FRA portion, in a normal operation sequence of the disc apparatus, it is not possible to reproduce the music data stored in the relevant parts even if other data has not been overwritten therein yet. Therefore, during an editing operation, if certain parts have erroneously had a data deletion operation performed partially or completely thereon, it is not possible to restore and thus reproduce relevant music data.
Further, in a case of recording a new tune, after relevant music data has been stored in the user data region, information of the UTOC region is modified accordingly. Therefore, when the operation is unexpectedly interrupted due to some cause such as power supply disconnection during a music tune recording operation, even if music data has been recorded in the user data region, because information of the UTOC region has not been accordingly modified yet and thus relevant parts of the user data region still belong to the P-FRA, it is not possible to reproduce the recorded music data.